Method for the permanent making of toothed belts

ABSTRACT

Permanent markings are formed on an elastomeric toothed belt for alignment of the drive system in which the belt is to be used by the application of strips of colored elastomeric material transversely across the belt in predetermined relationship with the belt teeth or gaps prior to the curing of the belt. The colored material enters into a firm bond with the elastomer of the belt upon curing.

United States Patent [191 Vossen [451 Nov. 13, 1973 METHOD FOR THEPERMANENT MAKING OF TOOTHED BELTS [75] Inventor: Karl Vossen, Aachen,Germany [73] Assignee: Uniroyal Englebert Deutschland AG, Aachen,Germany 1221 Filed; Sept. 22, 1970 121] App]. No.: 74,428

[52] US. Cl 156/140, 74/216.5, 74/232, 123/195 A, 156/257, 156/268,L56/265,

[51] Int. Cl B29h 7/22 [58] Field of Search 156/293, 298, 137-142,156/244, 257, 268, 277, 278, 280, 390, 450, 156/460, 471, 500, 514;74/2165, 232, 233; 161/4139 [56] References Cited UNITED STATES PATENTSVerges et a1 156/137 X 3,078,206 2/1963 Skura 156/140 2,099,126 11/1937Larsen 156/293 X 3,218,208 11/1965 Molen 156/293 X OTHER PUBLICATIONS1957 Ford Truck Shop Manual, Index page, pages 1-48, l-49, Copyright1957.

Primary Examiner-Alfred L. Leavitt Assistant Examiner-C. B. CosbyAttorney-Steven H. Bazerman [57] ABSTRACT Permanent markings are formedon an elastomeric toothed belt for alignment of the drive system inwhich the belt is to be used by the application of strips of coloredelastomeric material transversely across the belt in predeterminedrelationship with the belt teeth or gaps prior to the curing of thebelt. The colored material enters into a firm bond with the elastomer ofthe belt upon curing.

6 Claims, 5 Drawing Figures METHOD FOR THE PERMANENT MAKING OF TOOTI-IEDBELTS BACKGROUND OF THE INVENTION This invention relates to an apparatusand a method for the marking of elastomeric toothed belts and moreparticularly to the placing of markings on such'belts prior to theircuring to form durable markings without damage to the strength of thebelt.

The terms elastomer and elastomeric are used herein to designate naturalor synthetic rubber compositions, organic plastics having similarphysical characteristics, and mixtures of such materials.

Power transmission belts consisting of a toothed elastomeric body with anon-stretchable load supporting filament, such as seen in US. Pat. No.2,507,852 issued to R. Y. Case on May 16, 1950, are finding wider fieldsof application, particularly in the replacing of gear and chain drives.Because of the engagement accuracy and nonstretch characteristics ofsuch belts, they are suited for applications in which the pulleys,drives and the like to be interconnected by the belt have preciselydetermined angular relationships which must be maintained duringoperation. For example, toothed belts have been used to replace thetraditional camshaft drives in internal combustion engines. The camshaftmust be brought into a predetermined position relative to the crankshaftand must maintain that position throughout its operation. It istherefore desirable to provide toothed belts with spaced markings ontheir back in predetermined coordination with the belt teeth foralignment of the drive system in which the belt operates.

SUMMARY OF THE INVENTION It is the object of the present invention toprovide apparatus and a method for applying durable markings to thebelts for alignment of the drive system in which the belt is to be usedin a simple and inexpensive manner.

According to the present invention permanent markings are formed by theapplication of strips of colored material transversely across the beltcarcass in predetermined relationship with the belt teeth or gaps priorto curing of the belt. The material is such that upon hardening itenters into a firm bond with the elastomer of the belt. A propermaterial would be for example a dyed elastomer which is curedconcurrently with the belt carcass. In most applications the elastomershould be the same as that used in the belt body with the addition of adye for coloring. As a result, the marking substance forms a homogeneousunit with the rest of the belt after curing. Of course, separate colorsfor strips at different positions for allignment of each 'of the pulleysin the system may be provided.

Since the application of the marking is prior to curing, the belt may benotched to allow the use of a thick layer of marking material. Such deepapplication increases the durability of the marking and guarantees thatin those cases where the back of the belt blank is ground after curingfor accuracy or other reasons, the markings will not be removed. Sincethe marking substance is applied prior to curing, there is no dangerthat the belt will be weakened by the lacing of the marking material. Ofcourse, such weakening could happen with the application of the markingafter the curing of the belt.

While the belt may be marked by injecting dye directly into the back ofthe belt carcass, it is preferable to apply the marking in the form ofstrips of colored elastomeric substance. Such strips may be applied bythe spraying, extruding or the placing of preformed strips of elastomerin grooves in the belt back. If preformed strips of marking material areto be directly laid in the grooves, they will hold their shape better ifthey are partially cured before application or if inserts of anothermore rigid material are placed in the centers of the strips.

The present invention may be implemented by a device which is correlatedwith the teeth of the belt by a chucking and measuring means. A markingmeans would be mounted on a carriage which travels across the belt.After the build-up of the belt carcass, the marking device would bemoved across the back of the carcass at points selected by the chuckingand measuring means to spray, extrude, or otherwise apply to the back ofthe belt a dyed elastomeric substance. A short distance ahead of thespray nozzle or other elastomer applying means may be a device whichproduces a notch in the belt carcass into which the elastomer is laid. Aroller may also follow the spraying or other applying means in order toenbed the marking substance into the back of the belt by the applicationof pressure.

More simply, according to the present invention strips of markingmaterial may be laid across the buildup drum after the carcass of thebelt is formed but before the molding and curing of the belt. They areboth positioned and fastened by pins or slots on the external ends ofthe buildup drum. These attaching elements are spaced around thecircumference of the build-up drum and are positioned at predetermineddistances along the length of the carcass so that the resulting markingsare properly situated for alignment of the drive system. The strips willbe molded into the back of the belt during curing. As noted, to preventthe strips from moving during the molding operation and to allow deeperapplication of the marking material, grooves may be provided in the beltcarcass into which the strips are laid. If the strips are of such widthin relationship to the tooth width that they are not deformed laterallybeyond the tooth limits during the subsequent molding operation, a notchmay not be needed.

BRIEF DESCRIPTION OF THE DRAWINGS The method and apparatus areillustrated in the accompanying drawings in which:

FIG. 1 is a front view of a partly broken away buildup drum with acarcass on it;

FIG. 2 is a partial front view of another embodiment of build-up drawnaccording to the present invention with a belt carcass on it;

FIG. 3 is a cross section of a build-up drum with an unmolded carcasspositioned thereon in the process of being marked according to thepresent invention;

FIG. 4 is a longitudinal section of a tooth belt with a durable markingaccording to the present invention; and

FIG. 5 is a longitudinal section of another embodiment of the beltmarked according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The build-up drum and belt moldseen in FIG. 1 is of a type normally used in the construction of timingbelts and it, along with its method of use, is fully disclosed in U.S.Pat. No. 3,078,266 issued to W. A. Skura on Feb. 19, 1963. The drum 1has a central sector 15 on which the carcass is built. Equally spacedaround the circumference of center portion 15 are depressed per tions 6and raised portions 7 corresponding to the teeth and teeth gapsrespectively of a finished toothed belt. The central section 15 of thedrum is limited by end plates 4 which are firmly pressed against thecenter section 15 by means of nuts mounted on shaft 2. The shaft 2 ofthe build-up drum has centering holes 3 for mounting the drum in anappropriate holding device.

The end plates 4, may have annular grooves 16 having holes 12 for theventilation of the drum during curing. End portion 4 has a fasteningelement such as a slot 11 in which the end of the tensile member 9 isfastened.

Normally the unmolded belt carcass consists of a abrasion resistant,stretchable fabric 8, a tensile member 9 wound on the former and theelastomeric body 10 positioned on top of the tensile member 9. Duringmolding, the elastomeric body 10 is pressed through the inserts intogrooves 6 of the build-up drurn.

According to the present invention, as seen in H65. 1 and 2 the build-updrum 1 has on the end plates 4 fastening elements in the form of pins 13or slots 13a, onto or through which can be fastened the ends of strips14 of marking material. The strips 14 are fastened by tying them aroundpins 13 or on the outer side of slots 13a as seen in FIGS. 1 and 2respectively. The marking material is preferably of the same elastomericmaterial from which the belt is formed with the addition of a dye suchthat the strips 14 are colored differently from the belt. The fastenelements 13 and 13a are provided at predetermined spots on thecircumference of the buildup drum corresponding to the positioning ofthe markings on the back of the finished belt. These fastening elements13 and 13a may be marked or numbered to facilitate the use of differentcolored markings or sequence of markings. The fastening elements 13 and130 may also serve to align a notching device or a notch ruler by meansof which a notch 30 is produced across the belt and into which themarking strip 14 may be thereafter stretched as described herein.

As can be seen in FIG. 3, at points corresponding to the attaching means13 or 13a a notch 30 has been produced into which the preformed strip 14is positioned. Strip 14 may be partially cured or have a strengtheninginsert to insure that it will retain its shape. The strip 14 and notch30 may have various cross sectional shapes. FIG. 3 shows a strip 14 ofcircular cross section. The notch prevents the strip 14 from shiftingduring the molding operation, as well as allowing the use of a thickerstrip 14 of marking material.

FIG. 4 shows the shape of a belt according to the present inventionafter molding and curing. A flat marking strip 14 and its notch 30 havebeen molded and cured to produce a flat marking 24.

FlG. 5 illustrates the resulting belt when the marking strip 34 had acircular cross-section. In the embodiment of FIG. 5 the belt was groundafter its completion so that the resulting marking 25 has asemi-circular cross section. Grinding has the advantage of clearing themarking 25 since part of the carcass body 10 may have been pushed overthe stripe 14 during the molding operation.

The markings may also be applied to the belt by spraying or extruding adyed elastomer strip into the notch on the back of the belt carcass.This could be done by the use of a spraying or extruding apparatustransversely movable across the back of the belt carcass.

The marking strip 14 may be applied to the belt carcass without the useof a notch. The marking element 14 in the form ofa flat stripl4 isapplied across the belt carcass and thereafter during subsequent moldingand hardening operations is pressed and molded into the material of theback of the belt. As a result, strip 14 becomes part of the homogeneoussurface of the belt. If no notch is used, the strip should be of such awidth in comparison to the tooth width that it is not deformed laterallybeyond the tooth limits during the subsequent molding operation.

While the preferred form of this invention has been described, it is tobe understood that still other changes may be made without departingfrom the spirit of the invention and the scope of the appended claims.

Having thus described my invention, what I claim and desire to protectby letters patent is:

l. A method of marking elastomeric timing belts for alignment of thedrive system in which the belt is to be used consisting of making atleast one groove transversely across the back of the belt carcass at apoint corresponding to an alignment point for the belt in use prior tothe curing of a belt carcass; applying a strip of elastomer dyed a colordifferent from that of the belt in said groove the strip of dyedmaterial having a rigid reinforcing material, and thereafter curing thebelt carcass so that the strip of dyed elastomer enters into a firm bondwith the elastomer of the belt.

2. The method according to claim 1 wherein the strip of dyed material isreinforced by an insert of more rigid material.

3. A method of making a toothed belt having markings for alignment ofthe drive system in which the belt is to be used consisting of winding aload carrying band around the outer circumference of a cylindrical moldhaving axially extending grooves therein, placing a layer of uncuredelastomeric material adjacent to said band, making at lease one groovetransversely across the backside of the resulting belt carcass at apoint cor responding to the one to be marked; applying a strip of atleast partially cured elastomeric material dyed a color different fromthe belt in said groove; and applying heat and pressure to saidelastomeric material and said strip to force both said uncuredelastomeric materials into the mold such that they are both cured andthe strip forms a bond with the back surface of the resulting moldedtoothed belt.

4. The method according to claim 3 wherein the strip of dyed elastomeris formed before application to the belt carcass and is stretched acrossthe backside of the belt carcass.

5. The method according to claim 4 wherein the strip of dyed material isreinforced by an insert of more rigid material.

6. The method according to claim 4 wherein the strip of dyed material isreinforced by partially curing said strip before stretching said stripacross the belt carcass. t I t UNITED STATES PATENT AND TRADEMARK OFFICECERTIFICATE OF CORRECTION PATENT NO. 3,772,117 DATED July 9, 975 INVENTOR(S) KARL VOSSEN It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Claim 3, column 4, line Mt, the word "lease" should be replacedby--least--.

Signed and Sealed this ninth Day Of September 1975 [SEAL] Arrest.

RUTH C. MASON Arlestl'ng Officer C. MARSHALL DANN Commissioneruflarz'nrs and Trademarks

1. A method of marking elastomeric timing belts for alignment of thedrive system in which the belt is to be used consisting of making atleast one groove transversely across the back of the belt carcass at apoint corresponding to an alignment point for the belt in use prior tothe curing of a belt carcass; applying a strip of elastomer dyed a colordifferent from that of the belt in said groove the strip of dyedmaterial having a rigid reinforcing material, and thereafter curing thebelt carcass so that the strip of dyed elastomer enters into a firm bondwith the elastomer of the belt.
 2. The method according to claim 1wherein the strip of dyed material is reinforced by an insert of morerigid material.
 3. A method of making a toothed belt having markings foralignment of the drive system in which the belt is to be used consistingof winding a load carrying band around the outer circumference of acylindrical mold having axially extending grooves therein, placing alayer of uncured elastomeric material adjacent to said band, making atlease one groove transversely across the backside of the resulting beltcarcass at a point corresponding to the one to be marked; applying astrip of at least partially cured elastomeric material dyed a colordifferent from the belt in said groove; and applying heat and pressureto said elastomeric material and said strip to force both said uncuredelastomeric materials into the mold such that they are both cured andthe strip forms a bond with the back surface of the resulting moldedtoothed belt.
 4. The method according to claim 3 wherein the strip ofdyed elastomer is formed before application to the belt carcass and isstretched across the backside of the belt carcass.
 5. The methodaccording to claim 4 wherein the strip of dyed material is reinforced byan insert of more rigid material.
 6. The method according to claim 4wherein the strip of dyed material is reinforced by partially curingsaid strip before stretching said strip across the belt carcass.